The field of the invention relates generally to strobe lighting for digital photography. In particular, the field of the invention relates to a system and method for providing an interface unit that is used between a digital camera and one or more strobe units that provides greater flexibility in flash usage and enables photographers to achieve the correct amount of light output to properly expose photographs without having to change camera aperture and shutter speed settings. The strobe controller also provides interoperability for a wide variety of strobes.
Flash photography has become a very standard photographic technique in the past 30 years. Today all cameras except for the very cheapest disposable cameras come standard with a built in flash. Higher end cameras allow for the attachment of an accessory external flash unit to give the user greater flexibility in flash usage as well as greater light output. Generally these higher end cameras have a system to control both the internal and external flash automatically to achieve the correct photographic exposure. A system commonly referred to as xe2x80x9cThrough the Lensxe2x80x9d or TTL metering has become the default system in film cameras to control the flash output. In this system, the camera measures the light hitting the film plane and when enough light has been received to achieve the proper exposure, the flash unit is turned off. This system works through a connection between the camera and the strobe that allows for the transmission of two signals. One signal is used to start the flash and another is used to tell the flash unit when to extinguish.
This system is the de facto standard across a vast majority of film camera manufacturers that support automatic external flash control.
In the past few years digital cameras (cameras that store pictures on memory chips instead of chemically developed film) have become very popular and are beginning to replace the before mentioned film cameras in the marketplace. Unfortunately the digital cameras that do support external flash units often do not support the automatic flash control technique described above because of technological limitations. To work around this limitation, some manufacturers use a light sensor on the body of the camera to determine when enough light has been received to achieve the correct exposure and extinguish the flash. This system, however, is notoriously inaccurate because the light that hits the sensor can be very different than the light that actually enters the lens.
Other manufacturers use a double flash system where an initial short flash is used to light the scene and determine how much light is necessary for the main exposure. Next the main flash is activated in conjunction with the opening of the shutter on the camera. During the exposure, the camera shuts off the flash after a preset amount of time calculated from the initial pre-flash exposure. This system requires that the camera know exactly the operation of an external flash unit so that it can correlate the pre-flash exposure with the amount of light that will be released over time from an external strobe. This has led camera manufacturers to use proprietary communication protocols between the strobe and camera to achieve this automatic flash system. This in turn means that many older flash units do not work in an automatic fashion with these digital cameras. Thus, users must buy a new camera specific flash unit or use manual flash output which limits their exposure options.
Therefore what is needed is a strobe controller for a digital camera that can provide photographers a way to achieve greater flexibility in flash usage and achieve the correct amount of light output to properly expose photographs without having to change camera aperture and shutter speed settings.
In order to achieve the foregoing and other objectives, an aspect of the invention comprises a microprocessor based strobe controller that provides an interface between a digital camera and one or more existing strobe units. The strobe controller provides enhanced user control over the strobes by enabling the user to control the light outputs of a wide variety of different strobes. The strobe controller also provides interoperability for a plurality of strobes of different manufacturers. For example, the strobe controller enables a user to take pictures using digital TTL, manual bracketing based on TTL feedback and full manual operation with the ability to adjust light output over a plurality of levels with any TTL strobe.
In another aspect of the invention, the microprocessor based strobe controller enables external strobes to be adjusted separately. For example, one strobe may be adjusted to full power while another can be adjusted to half power. Also, strobes from different manufacturers can be made to interoperate with a desired camera.
In another aspect of the invention, the strobe controller is incorporated in a housing for operatively enclosing a digital camera for use underwater or in harsh environments. The strobe controller is integral with the housing, and the housing is configured to provide a communication link between the camera and one or more strobes. The housing further includes an intuitive user interface that accesses camera functions, strobe controller functions and gives visual strobe control feedback. The housing is also provided with a strobe control interface that enables a user to control one or more strobes from the housing.